Soccer is extremely widespread and played by both boys and girls at a young age (up until puberty or so), but there definitely is a gender gap after that. I'd guess that there are a lot of other sports that are almost solely played by boys, so boys tend to drift away from soccer, while there are fewer options for girls. (Though there are some - lacrosse and softball for a couple examples.)
Soccer is extremely widespread and played by both boys and girls at a young age (up until puberty or so), but there definitely is a gender gap after that. I'd guess that there are a lot of other sports that are almost solely played by boys, so boys tend to drift away from soccer, while there are fewer options for girls. (Though there are some - lacrosse and softball for a couple examples.)